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Discussion Starter #1 (Edited)
I pinched this mod of a member on the 250R forum and did it to my old repsol.
It's only taken me 15 months to get round to doing it to my 300R. :)

This is one for the fettlers and tinkerers who have access to a dremel or are patient with a round file.
Basically when Honda manufacture the header pipe and weld the larger diameter flange (that fits into your engines head) onto the end of the actual pipe, they leave a raised weld that hinders the flow of exhaust gases exiting the exhaust port. See photo.
P1010520.JPG

So if your fussy like myself you can remove this weld and allow a smoother passage for the gases which at high revs in particular aids efficiency. It will end up looking like this:
P1010521.JPG

P1010522.JPG


OK, so it's a bit like fitting the K&N air filter, you know it helps but its not going to transform your bike instantly into an arm stretching beast!
Folk who race bikes say it's the sum of a lot of small improvements that makes the difference.

Foot note: Make sure you replace the copper exhaust gasket when you re-fit the header pipe, they are cheap as chips.
 

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I pinched this mod of a member on the 250R forum and did it to my old repsol.
It's only taken me 15 months to get round to doing it to my 300R. :)

This is one for the fettlers and tinkerers who have access to a dremel or are patient with a round file.
Basically when Honda manufacture the header pipe and weld the larger diameter flange (that fits into your engines head) onto the end of the actual pipe, they leave a raised weld that hinders the flow of exhaust gases exiting the exhaust port. See photo.
View attachment 13457

So if your fussy like myself you can remove this weld and allow a smoother passage for the gases which at high revs in particular aids efficiency. It will end up looking like this:
View attachment 13465

View attachment 13473


OK, so it's a bit like fitting the K&N air filter, you know it helps but its not going to transform your bike instantly into an arm stretching beast!
Folk who race bikes say it's the sum of a lot of small improvements that makes the difference.

Foot note: Make sure you replace the copper exhaust gasket when you re-fit the header pipe, they are cheap as chips.
Nice tip Kiwi
A job for the spring weather me thinks :)
 

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another advantage of the single,,
only one pipe to deal with..

no need to rationalise caring for your motorcycle[!]
a definition of rational, to any motorcyclist..
 

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Kiwi, what dremel attachment did you use for this?. My exhaust is already showing surface rust at 4k right on the front section about 3-4 inches where my fender ext doesn't cover. Ordered some PJ1 exhaust paint and will remove exhaust completely and respray but thought I might do this mod.
 

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I pinched this mod of a member on the 250R forum and did it to my old repsol.
It's only taken me 15 months to get round to doing it to my 300R. :)

This is one for the fettlers and tinkerers who have access to a dremel or are patient with a round file.
Basically when Honda manufacture the header pipe and weld the larger diameter flange (that fits into your engines head) onto the end of the actual pipe, they leave a raised weld that hinders the flow of exhaust gases exiting the exhaust port. See photo.
View attachment 13457

So if your fussy like myself you can remove this weld and allow a smoother passage for the gases which at high revs in particular aids efficiency. It will end up looking like this:
View attachment 13465

View attachment 13473


OK, so it's a bit like fitting the K&N air filter, you know it helps but its not going to transform your bike instantly into an arm stretching beast!
Folk who race bikes say it's the sum of a lot of small improvements that makes the difference.

Foot note: Make sure you replace the copper exhaust gasket when you re-fit the header pipe, they are cheap as chips.
Great catch! If I already hadn't swapped my stock for a new header I would have done this.
 

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Kiwi, what dremel attachment did you use for this?. My exhaust is already showing surface rust at 4k right on the front section about 3-4 inches where my fender ext doesn't cover. Ordered some PJ1 exhaust paint and will remove exhaust completely and respray but thought I might do this mod.
Ahh the exact reason I changed mine to Stainless Steel right away. Everyone said why bother. Well it's ugly, weighs a ton and it rusts. :laugh:
 

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Ahh the exact reason I changed mine to Stainless Steel right away. Everyone said why bother. Well it's ugly, weighs a ton and it rusts. :laugh:
Would love to but there not as available here in blighty and they cost a lot more, if Honda had put a decent fender on it there wouldn't be a problem, also its a workhorse, Ive put levers on and pegs and am waiting for delivery of an R&G exhaust hanger and blanking plate to put on. I had to let a Scorpion exhaust for a 250 go on ebay this morning, it sold for £107. Scorpion refused to sell me a link pipe for my 300 otherwise I would have bidded for it, cant justify £300+ for an exhaust on the country roads I ride on.
 

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Would love to but there not as available here in blighty and they cost a lot more, if Honda had put a decent fender on it there wouldn't be a problem, also its a workhorse, Ive put levers on and pegs and am waiting for delivery of an R&G exhaust hanger and blanking plate to put on. I had to let a Scorpion exhaust for a 250 go on ebay this morning, it sold for £107. Scorpion refused to sell me a link pipe for my 300 otherwise I would have bidded for it, cant justify £300+ for an exhaust on the country roads I ride on.
Scorpion are one company I won't be using if that's their after sales service.
 

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Discussion Starter #10
Kiwi, what dremel attachment did you use for this?. My exhaust is already showing surface rust at 4k right on the front section about 3-4 inches where my fender ext doesn't cover. Ordered some PJ1 exhaust paint and will remove exhaust completely and respray but thought I might do this mod.
I used a cylindical shaped hardened steel one of 10 - 12mm diameter. If you were patient you could use a grinding stone type one. It took me about 5 - 10 minutes.
 

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How difficult is it to remove and re attach that longer exhaust piece? it's really rusted on mine, I painted the OEM slip on exhaust with black engine paint and it looks FANTASTIC, it's Held with three coats for one year too. But that longer tube is just nasty. I was thinking of removing it, sanding it, and painting it with brake caliper red (900°f), is that the right temp paint? Also, excellent mod, I'll be doing it while the pipe is removed.
 

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